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High aspect ratio micromechanical probe tips and methods of fabrication

a micromechanical and probe tip technology, applied in the field of microfabricated probe tips, can solve the problem of difficult etching of single pillar micromechanical tips, and achieve the effect of high aspect ratio

Active Publication Date: 2008-05-06
WISCONSIN ALUMNI RES FOUND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This method enables the fabrication of micromechanical tips with heights exceeding 30 μm, suitable for both AFM and SNMM applications, with improved vertical sidewall profiles and reduced parasitic capacitance, enhancing the resolution and sensitivity of metrology and imaging techniques.

Problems solved by technology

It has proven difficult to etch single pillar micromechanical tip having a height greater than about 20 μm while maintaining a vertical sidewall profile using deep reactive ion etching (DRIE) techniques.

Method used

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  • High aspect ratio micromechanical probe tips and methods of fabrication
  • High aspect ratio micromechanical probe tips and methods of fabrication
  • High aspect ratio micromechanical probe tips and methods of fabrication

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Embodiment Construction

[0035]With reference to the drawings, an exemplary process for producing micromechanical high aspect ratio tips in accordance with the invention is illustrated in schematic form in FIGS. 1-5.

[0036]First, as illustrated in FIG. 1, a 1 μm thick thermal oxide is grown on a Si (100) wafer 31 and an (e.g., 16 μm-diameter) oxide protective island 32 is patterned in the oxide by standard photolithography and buffered hydrofluoric (BHF) acid etch. The exposed Si is etched by RIE (SF6, 45 sccm, 50 mTorr, 100 W) to form a tip precursor 33 that will determine the final tip shape, as shown in FIG. 2. Alternatively, wet etching can be performed through use of an HNA solution mixture (i.e. HNO3:CH3COOH:HF (1:3:8 in volume ratio)). The etching selectivity of silicon in comparison with silicon dioxide is lower, however.

[0037]Next, a DRIE process is performed using a commercial STS® Multiplex ICP system (Surface Technology Systems, Redwood City, Calif.) to form a tip shaft 35 as illustrated in FIG. ...

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Abstract

A method of fabricating high aspect ratio micromechanical tips is provided. The method includes, but is not limited to, forming an etchant protective island on a surface of a silicon substrate with the silicon substrate exposed around the island; isotropically etching the silicon substrate by reactive ion etching around the protective island to partially undercut the silicon substrate beneath the protective island; anisotropically etching, by deep reactive ion etching, the silicon surrounding the island to a desired depth to define a tip shaft of the desired height supported at a base by the substrate; removing the protective island from the tip; and sharpening the top of the tip shaft to an apex. Using the method, micromechanical tips having heights greater than at least 30 μm have been obtained while maintaining the vertical sidewall necessary for both AFM and scanning near-field microwave microscopy (SNMM) profiling applications.

Description

REFERENCE TO GOVERNMENT RIGHTS[0001]This invention was made with United States government support awarded by the following agency: USAF / AFOSR F49620-03-1-0420. The United States government has certain rights in this invention.FIELD OF THE INVENTION[0002]This invention pertains generally to the field of micro-electro-mechanical systems (MEMS) and microfabrication techniques and particularly to microfabricated probe tips.BACKGROUND OF THE INVENTION[0003]Microfabricated ultra sharp tips may be utilized in various applications, including for example, electrostatic ion sources, atomic force microscopy, and spectroscopy. Very high aspect ratio atomic force microscope (AFM) tips, for example, are necessary to allow deep access to structural features during semiconductor processing and in the metrology of micro-electro-mechanical systems (MEMS) structures. S. Hosaka, et al., App. Surf. Sci., Vol. 188, 2002, pp. 467 et seq. Various techniques have been developed for the fabrication of high a...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H01L21/00G01Q10/00G01Q60/06G01Q60/22G01Q60/38G01Q70/16
CPCB82Y20/00B82Y35/00G01Q60/22G01Q60/38G01Q60/06Y10T428/24521
Inventor VAN DER WEIDE, DANIEL W.WANG, YAQIANG
Owner WISCONSIN ALUMNI RES FOUND